| Demonstration of optically pumped vertical cavity surface emitting lasers in the nitrides was a major breakthrough. We have also demonstrated high and reliable performance of electrical resonant cavity light emitting devices in nitride heterostructures despite all the challenges encountered. On one hand, we designed a relatively high Q cavity by depositing two dielectric mirrors on a structure where the substrate was removed, and current spreading issue was resolved using ITO as a transparent electrode. On the other, we were successful on structures where an in-situ AlGaN DBR, and an Esaki diode were embedded to provide both resonator quality and lateral hole current spreading. In both cases, modes as narrow as 0.6nm was obtained and we were able to pump devices over 10kA/cm2 where stimulated emission is expected. The results of the electrically injected devices suggest that these approaches are very promising for VCSEL demonstration. |
